This invention relates to means and a method for compartmentalizing the interior of a plastic enclosure and for selectively communicating the compartments so formed.
It is often desirable to compartmentalize a flexible transparent container, commonly known as a plastic bag, to separate contents and to control the flow of fluid either through the bag or between compartments. For example, U.S. Pat. No. 3,257,072 to Reynolds discloses a flexible plastic bag to store whole blood which is compartmentalized to separately store the plasma and red blood cells into which the whole blood is separated by centrifugal action. For that purpose, the plastic bag is divided by welding into several compartments which are communicable with one another through openings which can be closed by pinch type devices and, in fact, the entire bag across its width can be divided into separate compartments by an external clamping member which is applied across the bag.
Another example for controlled fluid flow within and out of a plastic bag is diclosed in application Ser. No. 972,730 filed on Dec. 26, 1978 and assigned to the same assignee as this application, now U.S. Pat. No. 4,237,881 to Beigler et al, in which the plastic bag is filled with a fluid suitable for the intravenous or enteric infusion into the human body. The plastic bag is divided, by a network of fluid passages which are integral with and welded into the plastic bag, into a large storage compartment for controlling fluid flow, and a discharge opening. Valve means are associated with the various fluid passages for selectively connecting the first and the second compartments, respectively, to the storage compartment and the discharge opening in one mode, and to the discharge opening and the storage compartment in another mode.
Even though plastic bags compartmentalized by welding accomplish the intended purpose, they have a number of disadvantages which detract from their efficiency, convenience, and ease of fluid control. For example, most plastic bags of the type referred to above are comprised of a pair of overlying thin flexible sheets of a thermoplastic material which are welded together at their peripheral edges to form the bag in the first instance. As will be explained hereinafter in more detail, the weld is formed by pressing a welding element to which a high frequency signal is applied into the material to produce a weld. Such welds create a bead which runs along either side of the weld and which is formed by the material displaced when the weld is made. This bead interferes with the pinch type devices and the clamping members devices of the type shown, for example, in Reynolds U.S. Pat. No. 3,257,072, to close openings and to divide the bag, and also with the valves of the type shown, for example, in Beigler et al U.S. Pat. No. 4,237,881, to close the fluid ducts because it acts as an obstruction to sealing across the bead.
In order to overcome the bead obstruction found at the weld edges, which exist at the edge of the bag or an opening, it is necessary to utilize pinch type devices and clamping members which are capable of exerting not only a force sufficiently strong to close an opening, but also sufficient to compress the bead so that it does not interfere with the closing or the opening. In other words, to separate an entire bag welded at its edges or to close a duct or passage created by a gap along an internal weld, requires the application of forces very much in excess of the normal forces required to divide the bag or to close passages since the clamping force must be large enough to compress the weld beads at the edges of the bag or the ends of the passage.
It is therefore a primary object of the present invention to compartmentalize the space between two sheets of thin, flexible thermoplastic material without welding.
It is a further object of the present invention to form a plastic bag with two or more compartments in which the edge of the compartments so formed, as well as any opening between compartments, are obstructionless so that they can be opened and closed with the application of normal or minor clamping forces making it unnecessary to apply forces to overcome the effect of the welding bead.
It is a further object of the present invention to provide a compartmentalized fluid enclosure with at least one valved interconnecting passage between compartments in which the compartment edges are formed impermanently by a pressurized ridge.
It is another object of the present invention to provide a normally welded plastic bag with means at localized portions along the peripheral edge which are obstructionless and which make the bag dividable by a pressurized ridge without the application of forces to compress the weld bead.
It is still a further object of the present invention to provide a means and method of forming a plastic bag and of internally compartmentalizing the plastic bag in a manner that is obstructionless across the compartment edges and which therefor allow for the convenient control of fluid between compartments.
It is another object of the present invention to form a plastic bag out of flexible materials which are not thermoplastic or readily sealed wherein the film material is sealed to a like material by means of the pressurized ridge.